Abstract: The present invention provides a rectangular building panel having shoulders along two sides thereof and units embedded in the panel for securing shuttering to two panels placed side-by-side so that columns and beams may be cast in the space between the shuttering and the panels which, when set, support the panels.

Abstract: A method of constructing floor castings for building comprising the steps of forming a frame or ribbing (6) of beams, supporting panels (1) between the beams to provide substantially the lower surface of the floor at a level below the lower edges of the beams, temporarily securing flat bridging means (9) against the lower surfaces of the panels to continuously bridge the gaps therebetween partially occupied by the supporting beams and pouring a layer (13) of concrete over the structure comprising the panels and beams to form, when set, a composite cast floor having a substantially smooth and continuous lower surface after removal of the bridging means.